THE CONTENTS OF ZOOPLANKTON OF THE DANUBE RIVER AND THE SAPROBIOLOGICAL ANALYSIS OF WATER QUALITY Republic Hydrometeorologic Service of Serbia, Belgrade, Serbia and Montenegro ABSTRACT ^a o S. & \urkovi} A. (2004). The contents of zooplankton of the Danube River and the saprobiological analysis of water quality. Proceedings of the 2 nd Congress of Ecologists of the Republic of Macedonia with International Participation, 25-29.10.2003, Ohrid. Special issues of Macedonian Ecological Society, Vol. 6, Skopje. In this article, the results on zooplankton analysis of the Danube river are presented as well as the saprobiological characteristics of water flow. The samples have been taken on 19 localities in July 2002, during the March route examination of ecological status of the Danube river, which has been organized by Federal Hydrometeorologic Institute of Yugoslavia. The contents' and the structure's analysis of zooplankton community as well as the appraisal of water quality on the basis of bioindicators have been carried out in Republic Hydrometeorologic Service of Serbia. By the analysis of zooplankton contents quality, it has been concluded the presence of 74 taxa from 4 groups. The dominant group is Rotatoria due to the presence of the greatest number of taxa. The main constituents of the community are the species of the genera: Brachionus, Keratella, Polyarthra and Trichocerca. Protozoa is subdominant group in zooplankton of the Danube river, while Cladocera and Copepoda are represented with small number of taxa. The significant constituent of the community is also the larval stadium of species Dreissena polymorpha (Lamellibranchiata). By saprobiological analysis of zooplankton, it has been concluded that the greatest number of indicatory organisms belongs to oligo-beta-mesosaprobionts and beta-alfa mesosaprobionts. The values of saprobic indexes are mainly within the range of beta-mesosaprobic zone. Introduction Through Serbia, the Danube river runs by its middle and the beginning of lower stretch. As the important water resource of the State, it is intensively used for water supply, melioration, electricity production, traffic, etc. The continuous risk of pollution due to the various factors makes the continuous examination of the river inevitable. In July 2002. under the March-rout examinations programme of the Danube river, the complex of hydrological, physical-chemical and hydrobiological have been carried out on 19 localities. The contents and structure's analyses of the plankton and benthos communities as well as the application of saprobiological system have been carried out with the aim of water quality determination, on the basis of these parameters. In the laboratory of Republic Hidrometeorologic Service of Serbia, the qualitative and the quantitative analyses of zooplankton have been carried out as well as the separation of indicatory organisms and saprobiological valorization of water quality on the basis of this community. Material and methods Water sampling for biological analyses have been done on 19 locations on the Danube river: Neštin (1), Novi Sad (2), Slankamen (3), Surduk (4), Zemun (5), Bela Stena (6), Ritopek (7), Smederevo (8), Ušće Velike Morave (9), Kostolac (10), Ram (11), Veliko Gradište (12), Brnjica (13), Dobra (14), Lepenski Vir (15), Donji Milanovac (16), Tekija (17), Mala Vrbica (18) and Mali Štrbac (19). These samples have been taken from 03.07.-17.07.2002. On each locality the samples have been taken from 4-5 spots on cross section from the depth of 0.5m, by hydrobiological bottle of 4.5 l volume and have been filtered through the plankton net of 25 µm mesh size. The samples have been conserved by addition of formaldehyde to the final concentration of 4%. The composite sample, whose volume matches the sum of filtered water volumes by spots, has been made for each locality. The zooplankton organisms have been determinate under the light microscope Carl-Zeiss, Amplival type and under binocular magnifying glass Leica by making preparations in glycerin solution, which have been 242 Zbornik na trudovi od 2-ot Kongres na ekolozite na Makedonija
The contents of zooplankton of the Danube River and the saprobiological analysis of water quality microscoped. The determination has gone to species level higher and lower taxonomic categories with use of certain keys especially for each analysed zooplankton group. Percentile presence of taxon has been calculated concerning the total number of individual organisms in certain sample volume. Relative numerosity (abundance) of zooplankton has been calculated sixth degree scale Magyar Szabvany 12756 (1998). Saprobiological valorization has been given using indicator organisms' list SEV (1977) and saprobiological method of determination of saprobic index S Pantle-Buck (1955). Results and assessment By the qualitative analysis of zooplankton (Tab. 1) it has been determined the existence of 74 taxa from the four groups: Protozoa (13 taxa), Rotatoria (47 taxa), Cladocera (9 taxa) and Copepoda (5 taxa). The determination has been made to the level of species, higher and lower taxonomic categories. The qualitative and the quantitative analysis show that Rotatoria is the dominant group in zooplankton of the Danube river that is in accordance with examination data Pujin, V. et. al. (1994); Simić, S. et. al. (1997) their percentile presence varied from 40.7% on locality Lepenski Vir up to 88.4% on locality Ritopek. (Fig. 1). The representatives of Rotatoria are mainly cosmopolitan species that, according to examination data Gulyas, P. (2002), can be found along the whole stretch of the Danube. From Rotatoria group the highest relative numerosity had the species: Brachionus calyciflorus f. amphiceros, Trichocerca rattus, Keratella cochlearis, K. cochlearis var. tecta and Polyartra vulgaris. Some of the taxa from this group of organisms have not been determined due to spasm of the individuals through conservation of the sample. Protozoa are subdominant group in Danube zooplankton. Their percentile presence varied from 1.65 % on Tekija locality up to 43.4% on Novi Sad locality (Fig. 1). In this group, the highest numerosity belongs to species of genera Carchesium, Vorticella and Staurophrya.The determination of Protozoa has been carried out by the use of very poor and old literature, because of the lack of modern keys and the fact that no one in Serbia deals with that group of organisms, who happen to have very rich presence in upper Danube flow through our country. The groups of Cladocera and Copepoda are present with low number of taxa. The species Moina micrura (Cladocera) and Acanthocyclops robustus (Copepoda) were in a higher presence only on few localities. The larva Nauplius, the stadium in development of Copepoda, on certain localities is present with somewhat higher relative numerosity. The results show that in the period of examination of Danube flow through our country from Neštin to Zemun, the higher relative numerosity of species from Protozoa and Rotatoria groups is notified, as well as that on Bela Stena locality (the first locality downstream Zemun) the considerable decrease of relative numerosity of the most taxa notified, specially the dominant taxa of genera Brachionus, Trichocerca, Carchesium and Vorticella. The relative numerosities of species from genus Keratella and species Polyarthra vulgaris downstream Zemun locality are held on more or less even level up to Kostolac locality, and downstream this locality their relative numerosity is also considerably decreased. Downstream this locality all the representatives of the groups mentioned above are present mainly individually or with low relative numerosity, except of the species Polyarthra vulgaris which is only additionally on Tekija locality present with high relative numerosity. The representatives of the group Fig. 1. Percentile presence of certain groups in zooplankton of the Danube river in July 2002. Proceedings of the 2 nd Congress of Ecologists of Macedonia 243
Cladocera and Copepoda are present only individually on localities from Neštin to Zemun. Only larva Nauplius has somewhat higher relative numerosity on Zemun locality. The representatives of Cladocera and Copepoda with somewhat higher relative numerosity are present in lower Danube stretch through our country, on Tekija and Mala Vrbica localities. On all localities examined in Danube zooplankton the larval levels of mussels Dreissena polymorpha (Lamellibranchiata). Their percentile presence is between 6.3-41.5 %. The Danube zooplankton, in the period of examination, in the qualitative and the quantitative view was far poorer than the phytoplankton (see Đurkovic, A. et. al., this Congress). Comparing the relative numerosities of the dominant species in the Danube plankton (Fig.3), it can be concluded that the maximum of numerosities of phytoplankton are followed by the maximum of zooplankton, that is in accordance with the results Gully s, P. (2002). For water quality assessment the saprobiological method by Pantle-Buck was used, and it is based on the statistical results manipulation of quantitative analysis of zooplankton community. The saprobic index varied between 2.16 on Novi Sad locality and 1.57 on D. Milanovac locality (Fig. 2). The highest number of detected taxa belongs to ο-β-meso-saprobionts, though the presence of β-α-meso-saprobionts and α-mesosaprobionts is also considerable, especially on the localities of Neštin, Novi Sad and Ušće Velike Morave. The saprobic index on these localities showed somewhat increased values, though those values are within the range of β-mesosaprobic environmental conditions. Only on Donji Milanovac locality the value of saprobic index matched the oligo-beta-mesosaprobic zone. Comparing saprobic indexes of the plankton communities, along the whole stretch of Danube (Fig. 2) it can be concluded that the saprobic index of phytoplankton shows somewhat higher values comparing to the values of saprobic index of zooplankton. Tab. 1. The qualitative contents of zooplankton of the Danube river and the relative numerosity of taxa. 244 Zbornik na trudovi od 2-ot Kongres na ekolozite na Makedonija
The contents of zooplankton of the Danube River and the saprobiological analysis of water quality Conclusion The aim of zooplankton examination was to determine qualitative and quantitative contents of this community as well as to determine water quality on the basis of indicatory species. Field examinations have been carried out on 19 localities on Danube in July 2002. In total, it has been determined 74 taxa of zooplancton. The highest number of taxa is within Rotatoria and Protozoa groups. The community of zooplankton is characterized by the domination of species from genera Brachionus, Trichocerca, Keratella and Polyarthra. On the localities from Neštin to Zemun it has been noted of increasing relative numerosity of dominant taxa downstream Zemun.Two less peaks of relative numerosity are on the localities of Kostolac and Tekija. Comparing the relative numerosities of dominant species in the Danube plankton, (see Đurković, A. et. al. this Congress), it can be concluded that the maximum of numerosities of phytoplankton are followed by the maximum of zooplankton. By saprobiological analysis of zooplankton, it has been concluded that the greatest number of indicato- Proceedings of the 2 nd Congress of Ecologists of Macedonia 245
Fig. 2. Saprobity index of phytoplankton and zooplankton of the Danube river in July 2002. ry organisms belongs to oligo-beta-mesosaprobionts and beta-alfa mesosaprobionts. The values of saprobic index are mainly within the range of beta-mesosaprobic zone. Literature Đurković, A. & Čađo, S. (2003). Phytoplankton analysis of the Danube River and water quality assessment on the basis of saprobiological examination, this Congress. Gulyas, P. (2002). Zooplancton.- In: Literàthy, P., Koller-Kreimel, V. & Liška, I. (Eds.), Joint Danube Survey, Technical Report of the International Commission for the Protection of the Danube River. Wienna, Austria. Pantle, R.,Buck, H. (1955). Die Biologische Uberwachung der Gewaser und die Darstellung Ergebinsse Gas und Wasserfach 96:604. Milovanović, D. & Živković, A. (1950). Prethodna saopštenja o sezonskim promenama organske produkcije u vodama plavne oblasti Dunava kod Apatina, Izvod iz zbornika radova Instituta za Ekologiju i Biogeografiju br. 1, Srpska Akademija Nauka, Beograd. Pujin, V., Tutundžić, V. & Ratajac, R. (1994). Zooplancton.-In: Janković, D., Jovičić, M. (Eds.), The Danube in Yugoslavia, contamination, protection and exploatation,.-belgrade: Institute for Biological Research Siniša Stanković ; Institute for Development of Water Resources Jaroslav Černi ; Federal Ministry of Science, Technology and Development; Ministry of Science and Technology of the Republic of Serbia; Federal Ministry for Environment Protection; Brussels: Commision of European Communities, 103-118, Belgrade. SEV (1977). Unificirovanie metodi isledovania kačestva vod. ΙΙΙ. Metodi biologičeskogo analiza vod. Indikatori saprobnosti, Moskva. Sladaček, V. (1973). System of water quality from the biological point of view E. Schweizerbet sche Verlagstbuchhondling, heft (7) Stuttgart,-pp 218. Fig. 3. Relative numerosity of the dominant species in the Danube river plankton in July 2002 246 Zbornik na trudovi od 2-ot Kongres na ekolozite na Makedonija